Phase behavior of polyglycerol didodecanoates in water

A phase diagram of a water-polyglyceryl didodecanoate ((C11)2Gn) system was constructed as a function of polyglycerol chain length (n) at 25 degrees C. The average number of dodecanoic acid residues attached to polyglycerol is in the range of 1.6-2.3, and unlike commercial long-chain polyglycerol surfactants, unreacted polyglycerols were removed in the surfactants used. With an increase in the polyglycerol chain, the surfactant changes from lipophilic to hydrophilic, and the type of self-organized structure also changes from lamellar liquid crystals to the aqueous micellar solution phase via hexagonal liquid crystals. However, a discontinuous micellar cubic phase does not appear in the phase diagram, while it is formed in a long poly(oxyethylene)-chain nonionic surfactant system. In a dilute region, a cloud point is observed at a moderate polyglycerol chain length, n approximate to 7. The cloud temperature is dramatically increased with a slight increase in hydrophilic chain because the dehydration of the hydrophilic chain length at high temperature is low compared with that of the poly(oxyethylene) chain. In other words, the phase behavior of (C11)2Gn is not very temperature sensitive. Three-phase microemulsion is formed in a water/(C11)2.3G7.3/m-xylene system. The three-phase temperature or HLB temperature is highly dependent on the polyglycerol chain length.     

Efficient sequential segment coupling using N-alkylcysteine-assisted thioesterification for glycopeptide dendrimer synthesis

A highly pure MUC1-derived glycopeptide dendrimer of 22 kDa was prepared by a sequential segment coupling, achieved by an N-alkylcysteine (NAC)-assisted thioesterification. The glycopeptide having C-terminal NAC was prepared by the Fmoc method and converted to the thioester by 3-mercaptopropionic acid treatment. The thioester was condensed with a lysine trimer carrying NAC to afford tetramer, which was then converted to the thioester. Two tetramers were condensed with ethylenediamine to give the octameric glycopeptide dendrimer.     

Carbon‐ion implantation improves the tribological properties of Co?Cr?Mo alloy against ultra‐high molecular weight polyethylene

Amorphous diamond‐like carbon (DLC) has drawn a great deal of attention for its superior wear properties against ultra‐high molecular weight polyethylene (UHMWPE). Its rate of wear, however, is not necessarily maintained within a specific range. The aim of this study was to evaluate the mechanical features and tribological properties of three types of surfaces: (i) uncoated, (ii) carbon‐ion implantation (CII)‐treated, and (iii) DLC‐film‐coated substrate. The surface alterations were carried out on cobalt–chrome (Co? Cr? Mo) alloy by the plasma‐source ion implantation (PSII) method. The wear properties and friction coefficient were estimated by a pin‐on‐plate wear‐tester. We found, as a result, that the implanted carbon penetrated the substrates in which good adhesion was expected. Though the surface modifications by CII and DLC hardened the surfaces, the surface with DLC was also roughened (R_a = 39 nm). In contrast, the surface modified by CII had a very smooth surface (R_a = 15 nm) and low friction coefficient (ranging from 0.15 to 0.20), resulting in a low rate of wear. Our findings suggest that CII on the Co? Cr? Mo alloy/UHMWPE pair offers potential benefits as a hard coating for artificial total‐joint arthroplasty. Copyright © 2008 John Wiley & Sons, Ltd.     

Recoil excitation of vibrational structure in the carbon 1s photoelectron spectrum of CF4

The carbon 1s photoelectron spectrum of CF4 measured at photon energies from 330 to 1500 eV shows significant contributions from nonsymmetric vibrational modes. These increase linearly as the photon energy increases. The excitation of these modes, which is not predicted in the usual Franck-Condon point of view, arises from the recoil momentum imparted to the carbon atom in the ionization process. A theory is presented for quantitative prediction of the recoil effect; the predictions of this theory are in agreement to the measurements. The experiments also yield the vibrational frequencies of the symmetric and asymmetric stretching modes in core-ionized CF4, the change in CF bond length upon ionization, -0.61 pm, and the Lorentzian linewidth of the carbon 1s hole, 67 meV.     

Cytotoxic iridoid aldehydes from Taiwanese Viburnum luzonicum

Four new iridoid aldehydes bearing (E)- or (Z)-p-coumaroyl group, luzonial A (1), luzonial B (2), luzonidial A (3), and luzonidial B (4), were isolated from a methanol extract of the dried leaves of Viburnum luzonicum collected in Kaoshiung, Taiwan and their structures were elucidated by analysis of spectroscopic data. Compounds 1-3 exhibited moderate inhibitory activity against HeLa S3 cancer cells.     

Author index to volume 51

Absolute cross sections for the quenching of Cd(³P₁) and Cd(³P₀) by acetylene, ethylene, propene, cis-2-butene and four fluoroethylenes have been determined by a phase-shift method. It was found that acetylene and olefins quench the triplet cadmium at almost gas-kinetic encounter, while the quenching rates for fluoroethylenes were found to decrease with the increase in the number of substituted fluorine atoms. It was also observed that these molecules do not cause intramultiplet mixing between Cd(³P₁) and Cd(³P₀). The causes of the decrease of the reactivities of fluoroethylenes are discussed.     

Hydrogen‐bonded complexes of 2‐pyridone with centrosymmetric and non‐centrosymmetric dicarboxylic acids

2‐Pyridone (2‐oxo­pyrimidine) forms hydrogen‐bonded com­plexes with di­carboxyl­ic acids, the molar ratio of 2‐pyridone/di­carboxyl­ic acid being 2:1 for the complexes with oxalic acid (ethanedioic acid), 2C₅H₅NO·C₂H₂O₄, (I), and trans‐β‐hydro­muconic acid (trans‐hex‐3‐enedioic acid), 2C₅H₅NO·C₆H₈O₄, (II), and 1:1 for the complexes with trans‐glutaconic acid (trans‐pent‐2‐enedioic acid), C₅H₅NO·C₅H₆O₄, (III), and l ‐­tartaric acid (l ‐2,3‐di­hydroxy­butane­dioic acid), C₅H₅NO·C₄H₆O₆·H₂O, (IV). Common features in the hydrogen‐bonding patterns were found for the centrosymmetric and non‐centrosymmetric acids, respectively. The 2‐pyridone mol­ecule takes the lactam form in these crystals.     

N2O and NO2 Formation in the Disproportionation of no over Ion Exchanged Cu-ZSM-5 at Lower Temperature

NO₃-type and NO₂-type adsorbed species are formed on Cu-ZSM-5 together with adsorbed O species at 523 K in the decomposition of NO accompanied by the evolution of N2, N₂O, and NO₂. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis of 5-Thio-D-Mannose

Abstract

5-Thio-D-mannose (1), the first 5-thiosugar found recently in nature, was synthesized in 12 steps from D-mannose.